NMR Investigation of the Weyl Semimetal TaAs

ORAL

Abstract

Weyl semimetals are expected to host topologically protected bulk states. Recently 181Ta nuclear quadrupolar resonance (NQR) was used as a bulk probe to investigate the band structure of the Weyl semimetal TaP near the Weyl nodes. [1] This is possible because nuclear spins couple to Weyl fermions via an anomalous hyperfine coupling influencing the temperature-dependent nuclear spin relaxation time T1. [2] Depending on the position of the chemical potential with respect to the Weyl nodes, the temperature-dependent relaxation rate is expected to deviate from the Korringa relation, where 1/T1T = constant. In this work we present 181Ta nuclear magnetic resonance (NMR) study of a single crystal TaAs Weyl semimetal, a material in which the chemical potential is typically closer to the Weyl nodes. The 1/T1T dependence of the ±3/2 <-> ±5/2 transition is measured using progressive saturation, and results are compared to theoretical calculations [2] and results on TaP [1]. The 181Ta quadrupole parameters and Knight shift are also determined from the field and temperature dependence of the resonance frequency.
[1] H. Yasuoka et al., Phys. Rev. Lett. 118, 236403 (2017).
[2] Z. Okvátovity et al., Phys. Rev. B 94, 245141 (2016).

*We acknowledge grants from the CFREF and FRQNT.

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Presenters

  • Arash Akbari-Sharbaf

    • Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC
    • Institut Quantique and Département de Physique, Université de Sherbrooke
    • Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada

Authors

  • Arash Akbari-Sharbaf

    • Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC
    • Institut Quantique and Département de Physique, Université de Sherbrooke
    • Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada

  • Aimé Verrier

    • Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC
    • Institut Quantique and Département de Physique, Université de Sherbrooke
    • Institut Quantique, Université de Sherbrooke

  • Nityan Nair

    • Physics, University of California, Berkeley
    • Department of Physics, University of California, Berkeley, California

  • James G. Analytis

    • Physics, University of California, Berkeley
    • University of California, Berkeley
    • Department of Physics, University of California, Berkeley
    • Department of Physics, University of California, Berkeley, California
    • University of California Berkeley

  • Jeffrey Quilliam

    • Department of Physics, Institut Quantique, Université de Sherbrooke, Sherbrooke, QC
    • Institut Quantique and Département de Physique, Université de Sherbrooke
    • Institut Quantique, Université de Sherbrooke
    • Universite de Sherbrooke
    • Département de Physique, Université de Sherbrooke, Sherbrooke, QC, Canada